The invention relates to a dispersing tool with a hollow shaft, which has an open, laterally slotted region at its free end that faces away from a drive and that is at the bottom in the position of use, and with an inner shaft, which can rotate in this hollow shaft and which has a dispersing rotor interacting with this hollow shaft in the region of the slotted end of the hollow shaft, wherein as the inner shaft rotates, it creates a pumping effect directed towards the free end.
A dispersing device of this type is known from U.S. Pat. No. 6,398,402 B1. In this publication, the inner shaft with a helical thread arranged thereon, which has the mentioned pumping effect in the direction towards the working end, is housed in a stationary, rigid hollow shaft, where both of these shafts are aligned with their working ends essentially downwards and arranged especially vertically in the position of use. This should prevent a pumping effect in the opposite direction due to the inner shaft and its formation while the inner shaft rotates. However, at the very high rpm values that are to be made available by such devices, there is the risk that displacements of the inner shaft will cause the thread to come into contact with the inner side of the hollow shaft, which could lead to worn and rubbed-off parts and these in turn could lead to undesired and disruptive fillers in the material to be dispersed. In addition, such an inner shaft can then become heavy if it is to be composed of metal. The thread on the inner shaft produces unbalanced masses, which differ over the profile of the inner shaft and which likewise can lead to undesired deformations and accordingly to contact with the hollow shaft, which is arranged at only a minimal distance.